disttask: grafana panel can't view/edit

[okJiang]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

run tidb, open grafana

2. What did you expect to see? (Required)

can be viewed/edited

3. What did you see instead (Required)

can't be viewed/edited

4. What is your TiDB version? (Required)

master